BeginnerTopic 13 of 102Manufacturing, Robotics & Systems
Casting
Pouring molten metal into moulds; sand, die and investment casting.
In depth
Molten metal is poured into a mould cavity, solidifies and is extracted. Processes: sand casting (flexible, cheap tooling), investment (precision), die casting (high volume Al, Zn), centrifugal, continuous casting. Considerations: gating, risers, shrinkage, porosity, draft and parting lines. Solidification time ∝(V/A)² (Chvorinov).
Key points
- Pattern allowances
- Defects: shrinkage, cold shuts
- Post-casting heat treatment
ExampleEngine blocks are sand cast in iron or die cast in aluminium.
Casting makes complex shapes in one step, so it is the start of many castings in engines, pumps, valves and sculpture.
What is Casting?
Pouring molten metal into moulds; sand, die and investment casting.
Why is it important to understand casting?
Casting makes complex shapes in one step, so it is the start of many castings in engines, pumps, valves and sculpture.
What is the difference between sand and die casting?
Sand casting uses a single-use mould and suits large or varied parts, while die casting injects metal into reusable steel dies for high volume and tight dimensions.
What is a common casting defect?
Porosity from trapped gas or shrinkage, which weakens the part and must be controlled by gating, venting and solidification design.
How is Casting used in practice?
Typical applications include making a cast iron engine block with internal passages, producing an aluminium housing for a pump with a complex shape and investment casting a turbine blade with fine cooling holes.
What should I learn before Casting?
Study "Metrology" first (topic 12 of 102 in Manufacturing, Robotics & Systems). It covers the groundwork this topic builds on.
What are the key points of Casting?
Pattern allowances. Defects: shrinkage, cold shuts. Post-casting heat treatment.
Can you give an example of Casting?
Engine blocks are sand cast in iron or die cast in aluminium.
What comes after Casting?
The next topic is "Forming and forging", which builds directly on this one.
How difficult is Casting?
It is classed as Beginner in Manufacturing, Robotics & Systems (topic 13 of 102). It is an entry-level topic. It relies only on basic school mathematics and the ideas introduced earlier in this discipline.